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• Classic-Fiction

Decompensated shock: the body’s compensatory mechanisms begin to fail and organ perfusion is severely reduced.

Irreversible shock: tissues become so deprived of oxygen that multiorgan failure occurs.

During compensated shock, some patients can lose up to 30% of their circulatory volume before the effects of hypovolaemia are reflected in the systolic blood pressure measurements or heart rate (Hughes 2004). Therefore, when assessing postoperative patients it is also useful to consider the early signs of reduced tissue perfusion in detecting signs of hypovolaemic shock (Anderson 2003, Hatfield and Tronson 2009, Jevon and Ewens 2007), which include:

restlessness, anxiety or confusion (as a result of cerebral hypoperfusion or hypoxia)

increased respiratory rate, becoming shallow (frequently occurring before signs of tachycardia and hypotension)

rising pulse rate (tachycardia as the heart attempts to compensate for the low circulatory blood volume)

low urine output of <0.5 mL/kg/h (as the kidneys experience a reduction in perfusion and pressure, which activate the renin-angiotensin system in an attempt to conserve fluid and increase circulatory blood volume)

pallor (pale, cyanotic skin) and later sweating

cool peripheries (pale, cyanotic lips and nailbed), resulting in a poor signal on the pulse oximeter

visible bleeding and haematoma from drains and wounds.

In most cases, if impending hypovolaemic shock is recognized and treated promptly, its progression through the aforementioned stages of shock can be circumvented (Hatfield and Tronson 2009). Irrespective of the cause of hypovolaemic shock, the aim of treatment is to restore adequate tissue perfusion (Hughes 2004). Excessive blood loss might require blood transfusion and occasionally surgical intervention. However, if signs are in the compensatory phase, fluid resuscitation with crystalloid or colloid and increased oxygenation to maintain saturation above 95% are sufficient to promote recovery for many patients.

Evidence-based approaches

Rationale

Although different surgical procedures require specific and specialist nursing care, the principles of postoperative care remain the same, underpinned by the application of evidence-based care. The nursing care given during the postoperative period is directed towards the prevention of those potential complications resulting from surgery and anaesthesia which might be anticipated to develop over a longer period of time. Consideration of the psychological and emotional aspects of recovery will of necessity be altered by the changed state of consciousness, awareness and knowledge of patients and their differing responses to surgery, diagnosis and treatment.

Principles of care

Fluid balance

There are several iatrogenic factors potentially contributing to fluid imbalance (circulating and tissue fluid volumes) in the postoperative patient. Anderson (2003) and Hatfield and Tronson (2009) suggest that these include:

preoperative bowel preparation

preoperative fasting times

potential fluid volume excess

fluid loss perioperatively

inappropriate fluid prescription

reduced intake postoperatively

ongoing losses from bleeding

paralytic ileus and/or vomiting.

Postoperatively it is essential that accurate fluid balance charts are maintained, outlining all fluid input (intravenous and oral) and output (e.g. urine, vomiting, wound exudate, drains, nasogastric (NG) drainage, stoma). This will facilitate the early identification of fluid loss or excess, which can be raised with a surgical colleague for appropriate management.

Some patients may require fluid replacement in the postoperative period to ensure an adequate fluid balance, avoiding dehydration and the resulting concentration of the blood that, along with venous stasis, is conducive to thrombus formation (Hughes 2004). Postoperative fluid replacements should be based on the following considerations (Doherty and Way 2006):

maintenance requirements

extra needs resulting from systemic factors (pyrexia)

losses from drains

requirements resulting